php HTTP 标头中使用的日期/时间格式
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The date/time format used in HTTP headers
提问by Desmond Hume
Which RFC describes the format used for date/time in the modern time HTTP headers, like "Last-Modified" and "If-Modified-Since", and how to generate a date/time string in PHP according to such format?
哪个 RFC 描述了现代 HTTP 标头中用于日期/时间的格式，例如“Last-Modified”和“If-Modified-Since”，以及如何根据这种格式在 PHP 中生成日期/时间字符串？
Some sources point to RFC 2822, which, as indicated by DateTimeclass, is using D, d M Y H:i:s Oformat, but from my tests, this format produces +0000instead of GMTat the end. I tried other timezone specifiers but none of them seems to put GMTat the end, the closest result I got was with UTC. However, as was shown by Firebug, all sites are using GMTin HTTP headers and not +0000or UTC.
一些来源指向 RFC 2822，正如DateTime类所指示的那样，它正在使用D, d M Y H:i:s O格式，但从我的测试来看，这种格式生成+0000而不是GMT最后。我尝试了其他时区说明符，但似乎没有一个放在GMT最后，我得到的最接近的结果是UTC. 但是，正如 Firebug 所示，所有站点都GMT在 HTTP 标头中使用，而不是使用+0000或UTC。
So what format is really used and how do I format date/time in the same way as other sites do?
那么真正使用的是什么格式，我如何以与其他网站相同的方式格式化日期/时间？
回答by Glavi?
As you can see here, Last-Modifiedheader has datetimes in RFC2616format.
正如您在此处看到的，Last-Modified标头具有RFC2616格式的日期时间。
In section 14.29 Last-Modifiedyou can see that date format should be:
在部分中，14.29 Last-Modified您可以看到日期格式应为：
"Last-Modified" ":" HTTP-date
An example of its use is
它的使用示例是
Last-Modified: Tue, 15 Nov 1994 12:45:26 GMT
Another quote from RFC2616 read more:
RFC2616 的另一个引用阅读更多：
All HTTP date/time stamps MUST be represented in Greenwich Mean Time (GMT), without exception.
所有 HTTP 日期/时间戳都必须以格林威治标准时间 (GMT) 表示，无一例外。
In PHP you can use format D, d M Y H:i:s Tif you use function gmdate()which always returns datetime in GMT offset/timeszone:
在 PHP 中，D, d M Y H:i:s T如果您使用gmdate()始终以 GMT 偏移量/时区返回日期时间的函数，则可以使用格式：
echo gmdate('D, d M Y H:i:s T');
If you wish to use DateTimeextension:
如果你想使用DateTime扩展：
$dt = new DateTime('UTC');
#$dt = new DateTime('2013-01-01 12:00:00', new DateTimezone('UTC'));
echo $dt->format('D, d M Y H:i:s \G\M\T');
回答by hanzi
Well, let's have a look at RFC 2616 which defines HTTP 1.1: http://tools.ietf.org/html/rfc2616#section-3.3
好吧，让我们看看定义 HTTP 1.1 的 RFC 2616：http: //tools.ietf.org/html/rfc2616#section-3.3
HTTP applications have historically allowed three different formats for the representation of date/time stamps:
Sun, 06 Nov 1994 08:49:37 GMT ; RFC 822, updated by RFC 1123 Sunday, 06-Nov-94 08:49:37 GMT ; RFC 850, obsoleted by RFC 1036 Sun Nov 6 08:49:37 1994 ; ANSI C's asctime() formatThe first format is preferred as an Internet standard and represents a fixed-length subset of that defined by RFC 1123 [8] (an update to RFC 822 [9]).
(...)
All HTTP date/time stamps MUST be represented in Greenwich Mean Time (GMT), without exception.
HTTP 应用程序历来允许使用三种不同的格式来表示日期/时间戳：
Sun, 06 Nov 1994 08:49:37 GMT ; RFC 822, updated by RFC 1123 Sunday, 06-Nov-94 08:49:37 GMT ; RFC 850, obsoleted by RFC 1036 Sun Nov 6 08:49:37 1994 ; ANSI C's asctime() format第一种格式是首选的 Internet 标准，代表 RFC 1123 [8]（对 RFC 822 [9] 的更新）定义的固定长度子集。
（……）
所有 HTTP 日期/时间戳都必须以格林威治标准时间 (GMT) 表示，无一例外。
So DateTime::COOKIEor Datetime::RFC850use a valid format. The preferred one according to the RFC would be D, d M Y H:i:s Twhich is not defined by any constant in the DateTimeclass.
所以DateTime::COOKIE或Datetime::RFC850使用有效的格式。根据 RFC 的首选D, d M Y H:i:s T是不由DateTime类中的任何常量定义的。
To make sure that GMT is used, the following code should suffice:
为了确保使用 GMT，以下代码就足够了：
gmdate('D, d M Y H:i:s T');
回答by Fraser
I'm pretty sure the (now) correct answer here is rfc7231 - section 7.1.1.1It specifies Date/Time Formats and is where the HTTP-datesemantics are defined.
我很确定这里的（现在）正确答案是rfc7231 - 第 7.1.1.1 节它指定了日期/时间格式并且是HTTP-date定义语义的地方。
HTTP-date = IMF-fixdate / obs-date
Also we can see that
我们也可以看到
When a sender generates a header field that contains one or more timestamps defined as HTTP-date, the sender MUSTgenerate those timestamps in the IMF-fixdateformat.
当发送方生成包含一个或多个定义为HTTP-date 的时间戳的标头字段时，发送方必须以IMF-fixdate格式生成这些时间戳。
So for a server sending a "modern time HTTP header"- where the value is a HTTP-datethe format is equivalent to the IMF-fixdateformat.
因此，对于发送“现代 HTTP 标头”的服务器 - 其中值是HTTP-date格式等同于IMF-fixdate格式。
So to answer the actual question.
所以要回答实际问题。
Which RFC describes the format used for date/time in the modern time HTTP headers
哪个 RFC 描述了现代 HTTP 标头中用于日期/时间的格式
You need to know the definition of IMF-fixdate- which is in rfc7231.
It also give the definition of obs-datetoo i.e rfc850-date/ asctime-date
您需要知道IMF-fixdate- 在 rfc7231 中的定义 。它还给出了obs-date太 ie rfc850-date/的定义asctime-date
IMF-fixdate = day-name "," SP date1 SP time-of-day SP GMT
; fixed length/zone/capitalization subset of the format
; see Section 3.3 of [RFC5322]
day-name = %x4D.6F.6E ; "Mon", case-sensitive
/ %x54.75.65 ; "Tue", case-sensitive
/ %x57.65.64 ; "Wed", case-sensitive
/ %x54.68.75 ; "Thu", case-sensitive
/ %x46.72.69 ; "Fri", case-sensitive
/ %x53.61.74 ; "Sat", case-sensitive
/ %x53.75.6E ; "Sun", case-sensitive
date1 = day SP month SP year
; e.g., 02 Jun 1982
day = 2DIGIT
month = %x4A.61.6E ; "Jan", case-sensitive
/ %x46.65.62 ; "Feb", case-sensitive
/ %x4D.61.72 ; "Mar", case-sensitive
/ %x41.70.72 ; "Apr", case-sensitive
/ %x4D.61.79 ; "May", case-sensitive
/ %x4A.75.6E ; "Jun", case-sensitive
/ %x4A.75.6C ; "Jul", case-sensitive
/ %x41.75.67 ; "Aug", case-sensitive
/ %x53.65.70 ; "Sep", case-sensitive
/ %x4F.63.74 ; "Oct", case-sensitive
/ %x4E.6F.76 ; "Nov", case-sensitive
/ %x44.65.63 ; "Dec", case-sensitive
year = 4DIGIT
GMT = %x47.4D.54 ; "GMT", case-sensitive
time-of-day = hour ":" minute ":" second
; 00:00:00 - 23:59:60 (leap second)
hour = 2DIGIT
minute = 2DIGIT
second = 2DIGIT
Obsolete formats:
obs-date = rfc850-date / asctime-date
rfc850-date = day-name-l "," SP date2 SP time-of-day SP GMT
date2 = day "-" month "-" 2DIGIT
; e.g., 02-Jun-82
day-name-l = %x4D.6F.6E.64.61.79 ; "Monday", case-sensitive
/ %x54.75.65.73.64.61.79 ; "Tuesday", case-sensitive
/ %x57.65.64.6E.65.73.64.61.79 ; "Wednesday", case-sensitive
/ %x54.68.75.72.73.64.61.79 ; "Thursday", case-sensitive
/ %x46.72.69.64.61.79 ; "Friday", case-sensitive
/ %x53.61.74.75.72.64.61.79 ; "Saturday", case-sensitive
/ %x53.75.6E.64.61.79 ; "Sunday", case-sensitive
asctime-date = day-name SP date3 SP time-of-day SP year
date3 = month SP ( 2DIGIT / ( SP 1DIGIT ))
; e.g., Jun 2
